Manufacture of steel.



ROBERT ABBOTT HADFIELD, OF SHEFFIELD, ENGLAND.

MANUFACTURE OF STEEL.

Specification of Letters Patent.

Eatented April 23, 1907.

Application fil d June 18,1904. Serial No. 213,131.

To ail whom, it may concern.-

Be it known that I, ROBERT ABBOTT HAD- FIELD, a subject of the King of. Great Britain, and a resident of Sheffield, county of York, England, have invented certain new and useful Improvements in the Manufacture of Steel, of which the following is a specification.

My invention relates to the manufacture of steel, and has for its purpose to produce a metal particularly adapted for structural and other purposes on account of its high tenacity, very high elastic limit, and great ductility and toughness. To this end I make the steel of a certain composition, as hereinafter fully set forth, using carbon, manganese, nickel, and chromium in proportions within certain limits, as stated below in detail.

A typical example of vmy steel contains .44% of carbon, 32% of manganese, 3.5% of nickel, and 1.71% of chromium. The proportions may be varied within certain limits, thus I may employ from to more or less carbon than indicated above, and the amount of chromium might vary from about 1% to 3%, and the nickel from about 2% to 5%. The percentage of manganese may also be varied but should. be kept low so as not to exceed say .25 or 3%.

The steel may be produced in various manners, as by the open-hearth process or in a crucible.

Steel of the composition above set forth has a high tenacity and a very high elastic limit, yet remarkable ductility and tough ness. These valuable properties may be enhanced by the following treatment One method of treatment is as follows The steel is carefully heated to a temperature between about 7 to 850 centigrade,

preferably 785, and quenched in oil. Then the steel is reheated to a temperature between about 620 and 630 and quenched in water. When so treated the steel has an elastic limit of over 100,000 lbs per square inch and a tensile strength of over 110,000 lbs per square inch.

Another method of treatment is as follows :The steel is carefully heated to a temperature of 710 centigrade and quenched in oil. Then the steel is reheated to 620 centigrade and quenched in water.

I. claim as my invention:

1. The herein described process of producing steel of great strength, which consists in first making steel containing manganese, nickel, and chromium, (the percentage of manganese being low) heating the steel to a temperature between about 7 50 to 850 centigrade, quenching in oil, reheating to a temperature between about 620 and 630, and quenching in water.

2. The herein described process of producing steel of great strength, which consists in first making steel containing manganese, nickel, and chromium, (the percent age of manganese being low)-heating the steel to a rela tively high temperature below its melting point, quenching in oil, reheating to a tem perature below that first employed, and quenching in water.

3. The herein described process of producing steel of great strength, which consists in first making steel containing manganese, nickel, and chromium, (the percentage of manganese being low) heating the steel to a relatively high temperature below its melt ing point, cooling it quickly, reheating to a temperature below that first employed, and I again cooling quickly.

4. The herein described process of increasing the strength of steel, containing manganese, nickel and chromium, the percentage of manganese being low which consists in heating it to a temperature between about 750 to 850 centigrade, quenching in oil, reheating to a temperature between about 620 and 630, and quenching the entire body of the steel in water.

5. The herein described process of increas ing the strength of steel, containing manganese, nickel and chromium, the percentage of manganese being low which consists in heating it to a relatively high temperature below its melting point, quenching in oil, reheating to a temperature below that first employed, and quenching the entire body of the steel in water.

6. The herein described process of increasingthe strength of steel, containing manga nese, nickel and chromium,.the percentage of manganese being low which consists in heating it to a relatively high temperature below its melting point, cooling it quickly, reheating to a temperature below that first employed, and again cooling the entire body of the steel quickly.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

ROBERT ABBOTT HADFIELD.

Witnesses:

EDWIN MORTIMER, I-I. MARTIN. 

